Yanagi missions

The Yanagi missions (柳作戦, Yanagi sakusen), or more formally the Submarine Missions to Germany (遣独潜水艦作戦, Kendoku sensuikan sakusen), were a series of submarine voyages undertaken by the Imperial Japanese Navy (IJN) during the Second World War, to exchange technology, skills and materials with Japan's Axis partners, principally Nazi Germany.

The aerial route that avoided Soviet airspace proved to be too much for existing aircraft to handle at that time, so most of the shipping was done by sea, from the Atlantic through the Indian Ocean to the Pacific.

In the spring of 1943, Hiroshi Oshima, the Japanese ambassador in Germany, had conversations with senior German officials in which they considered using submarines instead of surface ships.

The commander of the Kriegsmarine at the time, Grand Admiral Erich Raeder, opposed the plan as it would divert the navy from his priority of building more surface ships.

The Japanese control over Malaya and Indonesia led the German high command to consider sending U-boats through the Indian Ocean to southeast Asia.

In January 1943, Ambassador Oshima told Hitler that the Imperial Japanese Navy was building twenty large cargo submarines for the Yanagi missions.

[5][6] In June 1943 I-8 departed Kure with plans of the IJN's Type 95 torpedo, a reconnaissance aircraft and submarine equipment, and collected a cargo of tin, rubber and quinine at Singapore.

She also carried a spare crew of 48 men from Kure tasked with bringing back a German U-boat, U-1224, which the Kriegsmarine had transferred to the IJN for examination and reverse engineering.

[16] However, that night she was detected by radar-equipped Grumman TBF Avenger aircraft from an American hunter-killer group centered on the escort carrier USS Bogue, which dropped sonobuoys and "Fido" homing torpedoes, sinking I-52 with all hands (95 crew, 14 passengers and the three German sailors) near 15°16′N 39°55′W / 15.267°N 39.917°W / 15.267; -39.917, west of the Cape Verde Islands.

[21] In February 1944 U-1224, code-named 'Marco Polo II', was transferred to the IJN at Kiel, commissioned as RO-501 and set sail under a Japanese crew, to rendezvous with I-8 to refuel, and proceed to Penang with precious metals, uncut optical glass, and blueprints and models for building Type IX U-boats and Messerschmitt Me 163 Komet rocket planes.

[23] In March 1945 U-234 sailed from Kristiansand for Japan with 550kg (1,210 pounds) of uranium oxide, an Me 262 jet fighter, and plans for new electric torpedoes, the last attempt to be made, but she was overtaken by the German surrender and was taken into custody by the USN off Newfoundland.